If you can, buy a battery dry with the electrolyte on the side. Read the instructions for filling, capping, and charging and follow them closely.

Doing it incorrectly (as happens more often than not), pretty much cuts the life of a battery in half from the get-go.

A sealed AGM battery is a far better bet these days. Most batteries that come with acid separately are going to need constant maintenance (electrolyte level checking and topping up) throughout their lives, plus they are prone to spilling in the event of the bike ending up on its side.